Short Term Rentals are great but it takes a significant amount of upfront work and cost to execute them properly. 

Take ownership of your mistake and learn to do the proper due diligence recommended above😊

Make sure the “guts” of the toilets are working properly.

The one set of tenants did not even bat an eye (had not had a rent increase in 7+ years prior), and the other set appreciated it and moved out about 2 months after the rent increase (with proper notice). 

HOWEVER, if you already knew about a pre-existing roach issue and maybe failed to disclose it to them properly/didn't set correct expectations when they moved in, then it's on you. 

Proper transparent accounting is essential to any partnership, including when partnership is family.

[2] Rather than demo the garage, why not just install a 2nd proper septic system.[3] This guy must have some kind of car collection--what's his daily driver--some kind of "Far Out" Hot Rod?

Our attorney guided us to do an eviction notice with the proper amount of time (30 days, we did 45) to have them leave.  

You also need to know your local market and then you need to know how to properly and legally structure and perform the transaction.

They will be able to guide you properly in order to have the best shot of getting you where you want to be.